Abstract: A reversible braking mechanism is described, wherein a female member (5) receives a male member (3). One member (3, 5) carries a pair of bushes (19, 31) and the other member (3, 5) carries a pair of uni-directional roller bearings (21, 39) which engage the pair of bushes (19, 31). The uni-directional roller bearings (21, 39) are arranged in opposing directions, and a bush braking device (17) is selectively engageable with either of the bushes (19, 31).